Method and means for guiding aircraft



Sept. 16, 9941. ,w, BERG r 2,256,090

METHOD AND MEANS FOR GUIDING AIRCRAFT Filed Dec. 24, 1937 2 Sheets-Sheet l WALDWEFE'fi/ Y/(ARL may B Q "a ATTORNEY Sept; 16, 1941.

w. ILBERG ET AL METHOD AND MEANS FOR GUIDING AIRCRAFT Fil ed Dec.

24, 1937 2 Sheets-Sheet 2 \NV WALDE KA BY ENTOR MAR ILBERG IIZZRO RICH I-\TT ORNEY 2 older w-n switches whose construction may here serve as a step in the right direction. But also contact blocks may be utilized affording a longer life. Irrespective of the design of the contacts, it should be borne in mind in the first place that no appreciable variations in the wave resistance of the lines should exist.

Fig. 1 shows the radiators 5 with the contacts 6. They must be so arranged that according to.

Fig. 2 always two loop shaped radiation characteristics furnish a guide ray L1 and L2 re-' spectively. The angle formed by the two guide rays then represents the desired marking sector.

The switch arms operate independently of each other and are driven by means of cam disks 1 in conjunction with pusher rods 8 and pressure springs 9. is permitted to remain in a central position while the other arm carries out the switching and vice versa. The entire switching mechanism can, as to structure, be to a great extent a reproduction of the well designed valve drive of the combustion motor. Pressure spring, pusher and cam disks move in an oil bath.

The sequence of the switching performance can obviously be as desired. There also exists the possibility of providing a switching by using only a single cam disk.

In accordance with the invention the four directive radiators may be fed for instance during of a second. During this time each radiator is connected for /1 of a second at the most with the transmitter. But this time period must not be fully used for reasons that will be explained in detail at a later place. Hence, the switching is carried out in the rhythm of 25 cycles. This rapid switching sequence should to a high degree fulfill the requirements in regard to fading, etc. This switching arrangement can be built for absolutely reliable operation such as is known from the combustion engine in which much higher speeds of switching can be handled.

The transmitter antennas can be designed as defocussed parabolic radiators or preferably as plain surface radiators. In fact, it was found that the parabolic radiator causes considerable difliculties as regards the elimination of diagram peaks necessary for eliminating disturbing side guide rays and hitherto such difliculties could only be overcome by way of experimenting. However, in the plain surface radiator, an approximately peak-free diagram can be obtained theoretically and practically by a stepped feeding of the so-called pine tree antennas. For stepping up the amperage, the lead-ins may to advantage have small capacitances inserted therein aside from the resistors. Always two radiators are arranged in the box like fashion. This is appropriate in order that the two decimeter wave radiations forming together a guide ray have the same path length as regards the direct and reflected ray.

According to Fig. 3, the receiver arrangement comprises the antenna a, the detector path b, and a following tuned high-frequency amplifier c, affording a very effective amplification of the intermediate high-frequency carrier with a small number of tubes. It also is provided with automatic volume control whose time constant must, however, be greater than the switching sequence. The negative control potential and the alternating potential having audio-frequency are derived from a duo-diode. Following the detector path 11, a filter circuit e is inserted tuned In this way one switch arm contained. This frequency to the audio-frequency modulations of the transmitter and acting on the input of a single stage or double stage audio-frequency amplifier j. The use of an audio-frequency amplifier is for the reason of improving the selective properties of the audio-frequency filter circuit.

The proposition in accordance with the invention resides in that with the switching of the transmitter to four directive radiators the receiver output potential is switched in synchronism with four measuring instruments assigned to the individual radiators. The synchronism of the switching of the receiver can in principle be obtained in various ways, for instance, by means of a second transmitter which sends out the switching frequency in a rather unconcentrated state, thereby driving a synchronous motor at the receiver. In accordance with the invention the synchronizing of the switching at the place of reception is attained, while avoiding a second transmitter, by using the switching rhythm itself to provide the synchronizing. To this end, it is only necessary that in the radiated impulse sequence of the transmitter the 25 cycle note,for instance,appears. This can be achieved in that after each switching of the four directive radiators, a pause of about /5 of the time, i. e. a pause equal to the provided (Fig. 4). In this case in the signal sequence sent out, a frequency of 25 cycles is is likewise filtered out at the place of reception after the duo-diode, and transmitted from the circuit g to an amplifier It. With an output energy of about 1 watt asmall D. C. motor K consuming about 50 watts and which is fed from the current source 111. and whose normal number of revolutions is approximately 25 per second, can be synchronized with an accuracy of the angle of 10. In view of the fact that for reasons that will be given below, no particular requirements as regards, the synchronism at the receiver side need be fulfilled, the synchronizing arrangement for the switching of the guide ray can be constructed in a very simple manner.

The measuring instruments at the receiver side can be connected across collector slip rings or by means of sets of springs operated by cams. The marking of the guide ray may, as is obvious, also be indicated by means of differential instruments. In this case, in place of a bolometer or thermo-transformer, a rectifier cell having a steep slope will be of advantage. Through a special electrodynamic damping of the measuring instruments a sufficient inertia of the indication can be attained. In the example of construction according to Fig. 3, a commutator n, is assumed, connecting in succession the instruments i1, i2, is, and 2'4.

The exactness of the angle necessary for the synchronizing at the receiver side will now be brieflyinvestigated. If at the transmitter, the feeding of the directive radiators were to be carried out at intervals such that the individual impulses are switched without interruption, the synchronizing at the receiver side would have to be accurate to an extremely high degree. However, the method can be essentially simplified by inserting pauses of approximately 10 angle degrees in length. Then, the synchronizing at the receiver side is to take place with an accuracyof only :10 angle degrees. Any shift in the time of the switching of the indicating apparatus remaining within in the same manner. to all four this limit then extends measuring instrulength of an impulse is ,nected only if at the transmitter 'detrirnental';v

frequenc/y amplifier- 7 of Fl}? a n-the systnis y arranged;

ments, or; in: :other words: all fci-ir instruments;- arerthentswitehedz earlier-or :later by the same 1 timeutlt isipresumed that the motor' -eontinues to-zlnrove .uniformlyt -duringm a singl revolution such ascan beLreadily accomplished by. providing I 'Iheisyznchronizin'g: canin accordance with the-- invention;also: .be xcarriedwout in. that during the perioct ofisynchronizing the transmitteris modulatedizbyreanothen modulation frequency which is-.utiiized rastsuch at .the place of reception aften for obtaining thei syn'chronism.z Int-order to send out-the syn? chnonizin'g noteta fifth-directive radiator can-be briefiytgconnected to-the transmitter which covers" thez-sectorsrencloscd by lthe two guide rays."- Or thettwo liexterior guide ray antennas which like-- wisaccoverna wide angle can -be-connected--in For. the sake v of greater -sim-plicity,-'- however, ltheixmethod described above in which a zspecialiirequency is not --required,-appearsfto beipreferableh Fdri'thisimetho'd in accordance with a further" featurei'of; theninvention anind-icating 'instru ment 2'5 is provided, affording supervision of the" phasemositioha:In'thi's arrangement;- a fifth cam,

havinglzbeenzfiltered accordingly,

common or-islip .:1'ingc,:-';.0r.:lamella, is added to the four cams,:; orzslip' ings, or-co1iector lamellae and in :itsanormalxstate, i. e. in case of c'ompletesyn 'chronism, connectszthe said instrument to the receiver :outputljust at the time when the trans-1 mittens hash-its: synchronizing interval. This switching. is .carried: out directly followinathe' fourthx'rimpuls rand isterminated again just when :the: firstzimpulsesets in again. If apprc: pri atelzsynchronism exists I between the switching of ;.theiztransmitteizand receiver,- the instrument willwnotriurnish.nnindieatioh since it is-con-' is 4; .present *ribetween the synchronizing signals. Butts-if thetsynchronism shifts manner, the siinstrument either if :thei-niotor is in advance of its correct position,

or;.fromzthe fir'st impulse if the motor happens 'Ihezmagnitude of this deviation "is a measure-obthe slack inaccuracy of the syn Chl'O11iZHfi0I1.T1.-';Thl$ incomplete exactnesshas no ifect as long as it stays'within' i 10 angiegdegrees; but when it extends beyond this value the. guideiiraydndication is inaccurate.

Furthrmoreg1a blocking of theindicationisf carried out when the value of the allowable deviation oflth'esynchronism is exceeded. This can-be done-Micro instance, by inglsatci-thei fifth instrument circuit-1 b-ergiven'ibyewhich the automatic shutting down of-:the-guide rayindieation is brought to attention :byioptical or acoustic means.- The delay circuit 0. semester smoothing and delaying the blockingrpotentialp Moreover;thespotential appearing at the fifth instrument. may be utilized for improving the synchronizing action;-

ACcQrdingtoFigL-S, in place of four indicatinginstrumentstwo instruments can be provided in differentialiconnection. ;.In this arrangement the terminals 8 represent the output oi the audio' 11 ace; the indi side an interval somewhat in "any receives some vol-tageefroma the fourth impulse, for instance,

the voltage appear after having been amplified a'actuatingfla relay through delay" l0 whereby. all fourguide ray instruments willf-l-beidiseonnected Orshort-circuited. At *fllf samehtime, a luminous signal "qor the like can 75 blocking of the two instruments ai axiall the pointers of both instruments irid1cate di rectl-y thelposition ot thei:guide ray :Li and L2 shown '2. 'lnrorder to ext d' th'e': object of the invention directed toward eliminating as 1 far: s-ipossibl'e theiinstruments' at th'e receiv ,Sid e -Whmh m influence th indication of} the positionrof th ui e ray,l -it is -p'rop csed to res'ti ufl ints and- 'sets' 0f contactsatirereofmoy a singleind icating instru mente ATheJ arrangem'ent may in this casefor instance cents: ShOWn-"inFig'I-G wnerein a sing' l'e; rod-type glow tube t is" so excited -that the; magnitude' or luminescen depends -o n the volt age applied. Each directiveradiatoi of' thetrans mitterthen produces a certain lengtli "of --the luminescent path in accordance -withf the -intensit bf the receiving-field. In Figi'l'thindi ividu'al luminescent columns ar-e shown "situated adjacent each 'other-fi But since the switching of the transmitte' must-take place at a very high speefl tthe eye can not follow the fluctuations ofiith'e lluminous =co1u'mn' thus being unable} to 2 ,;estihiate th position of the receiver-in the -guide ray secto'r'i An" indication is, however, attained by means of a mirror when rotating in rrdntbr the midrescent tube,- said Wheel being' controlled by the g i-stransmitter in regard to synchronism and exact:

nes's ofitheanglel' In the -present casegthean rangement' may; however be essehtially simplifie The mirrors of thewhel are so set'that five 'adjacent "and I accurately-defined posi-- tions' o'f -the reflected-fluorescenttube; Four luminous 'stripes correspond to the four i assigned directive radiators of' th transmitter while" the fifth :iuminbusestripe permits of eontrolling 'the 40 synchronism 'nf the "-mirror'iwheela' The latter performance is such 'that this mirror secti-on is always in efi'ect when'thetransmitter has its interval between the synchronizing signals. 'In the nor-malstate'the-fifth fieldis dark inJthe t-.,;indi caticn ofthereceiver. But; if the synchro- I nism is somewhat disturbedythe fifthfield is luminous, the luminous portion increasing with 1 the magnitude ofthe deviation from synchronisnifof "the receiverii Since eachiof "the five .fieldswill be 25ti1iis illuminated during 1 one second? the" eye receives theimpriass'ion of four or five uniforinl'y illuminated fields which, how? ever, have a; different height in accordance'with the position of -the'-receiv in theguideray' sec-V Mtor. Obviously, in place of the mirronwheel; other-deviation systems 'known maybe used; for

must then be adapted-to thesesyste'msin a suit? able-manner.

tensiveand" short fluctuations owing to' the steamer effect, also the height of I the luminous column will follow these short fluctuations. entails, however, a blurredindicationl "[Ihere fore, it is furthermore proposed-to suppress these fluctuations of theindication by a 'phosphores cent =layer having after-glow;

In Fig. 8 a mode of constructi-on of thelmirror ,,Whee1 is shown. Small mirrors to are disposed withinshort distances at: angles-such that an,: image:aecording to :Fig. 11 appears on a screen '11. 1 In-place of theglow-' tubealso a Braun tube may --be-used.- ---At incompletesynchrnism of the;indication may in this cas'e be instance, the Nipkow'disk." The typ'e of deviation Since' the" output potential'may" undergo in-i'i obtained by means of a photo-electric cell arranged in the fifth field.

W e claim:

1. The method of guiding a vehicle which comprises transmitting in a plurality of at least partially overlapping beams, spaced impulses of radiant energy in a predetermined sequence, and modulated with a single frequency, consecutive impulses being radiated in different beams, receiving said impulses on said vehicle, demodulating said impulses, and generating a separate sensible indication of the relative amplitude of the modulation on each of said impulses, said indications being continuously sensible whereby the relative position of said vehicle with respect to said beams may be determined.

2. The method of guiding a vehicle which comprises transmitting in a plurality of at least partially overlapping beams, impulses of radiant energy in a predetermined sequence, and modulated with a single frequency, said impulses being separated by short blank intervals and consecutive impulses being radiated in diflerent beams, receiving said impulses on said vehicle, demodulating said impulses, and generating separate but simultaneously visible adjacent indications of the amplitudes of the modulation on each of said impulses whereby the relative position of said vehicle with respect to said beams may be determined.

3. The method of guiding a vehicle which comprises transmitting in a plurality of at least partially overlapping beams, spaced impulses of radiant energy in a predetermined sequence, and modulated with a single frequency, consecutive impulses being radiated in difierent beams, receiving said impulses on said vehicle, demodulating said impulses, and generating a continuously visible indication of the relative amplitudes of the modulation on said impulses whereby the relative position of said vehicle with respect to said beams may be determined.

4. A system of guiding vehicles by radiant energy which comprises a transmitting station having a plurality of separate directive radiators, means for sequentially energizing said radiators with spaced impulses of radiant energy whereby a plurality of overlapping guide rays are produced, a receiver for said impulses, a plurality of indicating instruments equal in number to the number of said directive radiators and means for sequentially switching said receiver to each of said indicating instruments in synchronism with the energization of said radiators.

5. A system of guiding vehicles by radiant energy which comprises a transmitter, a plurality of separate directive radiators, means for sequentially energizing said radiators from said transmitter with spaced impulses of radiant energy whereby a plurality of overlapping guide rays are produced, a receiver for said impulses, a plurality of indicating instruments equal in number to the number of said directive radiators and means for sequentially switching said receiver to each of said indicating instruments in synchronism with the energization of said radiators, said means for sequentially energizing said radiators comprising a contact connected to each radiator, a plurality of contact arms connected to said transmitter and so operating between said contacts that only one of said contacts is engaged by a contact arm at any instant, said arms each having a length equal to one-half the length of the operating wave whereessence by the arms which are not in engagement with a contact present no load on said transmitter.

6. A system of guiding vehicles by radiant energy which comprises a transmitter, a plurality of separate directive radiators, means for sequentially energizing said radiators from said transmitter with spaced impulses of radiant energy whereby a plurality of overlapping guide rays are produced, a receiver for said impulses, a plurality of indicating instruments equal in number to the number of said directive radiators and means for sequentially switching said receiver to each of said indicating instruments in synchronism with the energization of said radiators, said means for sequentially energizing said radiators comprising a contact connected to each radiator, a plurality of contact arms connected to said transmitter, motor driven cam means for operating said arms between said contacts so that only one of said contacts is engaged by a contact arm at any instant, said arms each having a length equal to one half the length of the operating wave whereby the arms which are not in engagement with a contact present no load on said transmitter.

'7. A system of guiding vehicles by radiant energy which comprises a transmitter, a plurality of separate directive radiators, means for sequentially energizing said radiators from said transmitter with spaced impulses of radiant energy whereby a plurality of overlapping guide rays are produced, all of said impulses being modulated with the same frequency, a receiver for said impulses, said receiver containing means for demodulating said impulses, and means for giving separate but closely adjacent continuously visible indications of the relative amplitude of the modulation on said impulses received by said receiver.

8. A system of guiding vehicles by radiant energy which comprises a transmitter, a plurality of separate directive radiators, means for sequentially energizing said radiators from said transmitter with spaced impulses of radiant energy whereby a plurality of overlapping guide rays are produced, a receiver for said impulses and means for giving separate but closely adacent visible indication of the relative amplitude of said impulses received by said receiver, sa d means comprising a glow tube energized by said receiver and a mirror wheel rotated in synchronism with the energization of said radiators.

9. A system of guiding vehicles by radiant energy which comprises a transmitter, a plurality of separate directive radiators, means for sequentially energizing said radiators from said transmitter with spaced impulses of radiant energy whereby a plurality of overlapping guide rays are produced, a receiver for said impulses and means for giving separate but closely adjacent visible indication of the relative amplitude of said impulses received by said receiver, said means comprising a glow tube energized by said receiver, a mirror wheel rotated in synchronism with the energization of said radiators and a translucent screen scanned by said mirror wheel upon which luminous indications of the relative amplitude of said impulses are received.

10. A system as defined in claim 9 in which said glow tube is coated with a phosphorescent material whereby rapid variations in the amplitude of said impulses are marked out.

11. A system of guiding vehicles by radiant energy which comprises a transmitting station erating said switching having a plurality of separate directive radiators,

j means, for sequentially energizing said radiators with spaced impulses of radiant energy whereby v a plurality of overlapping guide rays are produced, a receiver for said impulses, a plurality of indicating instruments equal in number to the number of said directive radiators, means for sequentially switching said receiver to each of said indicating instrumentsin synchronism with the energization of said radiators, and

means for maintaining the synchronism comprising means for radiating a separate non-directive synchronizing impulse between a pair of said spaced impulses, and means for applying said synchronizing impulse to amotor for opmeans, 12. Asystem of guiding vehicles by radiant energy which comprises a transmitting station having a plurality of separate directive radiators,

means for sequentially energizingsaid radiators with spaced impulses of radiant energy whereby a plurality of overlapping guide rays are produced, a receiver for said impulses, a plurality of indicating instruments equal in number to I the number of said directive radiators and means I 'for sequentially switching said receiver to each of said indicating instruments in synchronism rective synchronizing impulse between a pair of said spaced impulses, means for applying 'saidflfi synchronizing impulse to a motor for operating;

said switching means, a separate indicating instrument also responsive to said synchronizing impulse and means responsive to an absence of said synchronizing impulse for disabling said plurality of indicating instruments.

13. In a radiant energy system wherein a high frequency source is selectively connected to a plurality of utilization means, a switch hav-- ing fixed contacts connected to said means and,

a movable switch arm selectively engageable with said fixed contacts and having a position in which said arm is not in engagement with connected to said source, length equal to an integral the length of the operating said arm having a multiple of a half not in engagement with said fixed contacts.

WALDEMAR! ILBERG. KARL Ron-RICH.

with the energization of said radiators, and. means for maintaining the synchronism com--v prising means for radiating a separate'non-di jany of said contacts, said movable switch arm being wave whereby said 1 arm presents no load to said source when it is 

